1. Field of the Invention
The present invention relates to a viscous fluid coupling for connecting the engine of an automotive vehicle to a cooling fan for the engine radiator, and more particularly to a viscous fluid coupling of the temperature responsive type in which a bimetal coil located on the exterior of a rotatable casing operates a valve for controlling the flow of viscous fluid within the casing in response to the temperature of air flowing through the engine radiator.
2. Description of the Prior Art
In conventional temperature responsive viscous fluid couplings of this type, a bimetal coil is located on the exterior of a rotatable casing connected to a cooling fan. The bimetal coil is responsive to the temperature of air flowing through the engine radiator, and has an inner end operatively connected to a valve for controlling the flow of viscous fluid within the casing. An outer end extends radially outwardly and is fixedly or slidably received within a radial slot formed in the casing or a holder fixed to the casing. In this arrangement, stress concentrations arise in the bent portion defining the outer end, and in the coiled portion of the bimetal coil when the bimetal coil resonates to the torsional vibration transmitted from an engine to the casing. These stress concentrations can cause breakage of the bimetal coil. In addition, the resonance of the bimetal coil causes radial displacement of the outer end of the bimetal coil or wear on the outer end of the bimetal coil which, in turn, causes an objectionable varying of the temperature responsive characteristics of the coupling.
Accordingly, it is a primary object of this invention to reduce the amount of vibrational resonance in the bimetal coil of a viscous fluid coupling.
It is a further object of the present invention to improve the connection between the outer end of a bimetal coil in a viscous fluid coupling and a rotatable casing by pivotally connecting the bimetal coil to the casing.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.